'Arrow' EP: Lazarus Pit "Consequences" Reverberate Into Season 4

The much-teased Lazarus Pit will be front-and-center in Wednesday's episode, marking the first time the show will dive headfirst into DC's supernatural mythology. In the comics, Ra's al Ghul uses the Lazarus Pit to rejuvenate himself and even bring people back from the dead. In an earlier episode, he healed one of his own wounds using it.

In Wednesday's hour, Oliver (Stephen Amell) must consider using the supernatural pit to revive Thea (Willa Holland), whom Ra's al Ghul (Matt Nable) brutally attacked in last week's episode. The attack was all part of Ra's' ongoing quest to get Oliver to take over his mantle and become the new leader of the League of Assassins.

Even if Oliver successfully uses the pit to heal Thea's wounds, don't expect it to be a tidy resolution. Thea's father Merlyn (John Barrowman) warns in the trailer (below) that the Lazarus Pit changes people.

"Everything in the show has consequences, and that's something we've been consistent about," executive producer Marc Guggenheim tells The Hollywood Reporter.

With four episodes left in the season, the hour sets up the year's end game, and its events reverberate much further.

"It's something you will continue to see not just through the end of season three, but into season four," Guggenheim says of the episode's big moves.

Stay tuned to The Live Feed following Wednesday's episode for a spoiler-filled postmortem with Guggenheim.